62% to 75% of breast cancer cases among white women were attributed to
known breast cancer risk factors, compared with only 7% to 36% of cases among
Hispanic women.

Hispanic women were more likely to have characteristics associated with
lower breast cancer risk, such as earlier age at first childbirth, having more
children, shorter height, less hormone use, and less alcohol consumption.

Among premenopausal women, taller height and family history of breast
cancer were associated with increased risk in white women, but not among
Hispanic women.

Among postmenopausal women, certain breast cancer risk factors in whites,
such as recent hormone therapy and younger age at the first occurrence of
menstruation, had no or little association with breast cancer in
Hispanics.

The researchers say the findings suggest that many of the risk factors
studied up to now explain fewer of the breast cancer cases that arise in
Hispanic women compared with white women.

"These differences are likely to contribute to disparities in breast cancer
incidence rates and could potentially reflect differences in breast cancer
development among these ethnic groups," study researcher Lisa Hines, ScD, of
the University of Colorado, says in a news release.

Ethnic differences in genetic, environmental, or lifestyle factors may
affect the susceptibility of women to the development of breast cancer.

Estimating Breast Cancer Risk

The researchers also conclude that the study's findings indicate that the
use of models to estimate a woman's risk of breast cancer, developed from
previous research involving non-Hispanic white populations, needs to be
evaluated among other ethnic and racial populations.

Hines says that it is not fully understood why breast cancer occurs more
frequently in certain ethnic and racial groups, but that previous studies have
shown that white women have a higher incidence of breast cancer than Hispanic
women.